About 62 per cent of Canadian adults – more than 20 million people – are now either overweight or obese. That’s an awfully high number of Canadians who seem to need help with their weight. It’s the number trotted out by health experts when they want to stress the inexorable rise of obesity.

But are we exaggerating the ranks of overweight Canadians? It’s an important question because we hear that too many Canadians are getting fat, usually against their will. If that’s the case, it opens the door for governments to tax and regulate the foods and drink we consume. Then again, bad news about rising obesity is good news for the obesity-industry complex.

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First is the problem with the universal measurement of weight itself, body mass index. A healthy BMI is between 18.5 and 24.9. Anything below that and you’re too thin. Twenty-five to 30 is overweight, and anything above 30 is obese, broken down into a further three categories of severity.

But BMI can’t distinguish between fat and muscle. That’s why a lot of professional athletes are classified as obese. In the late 1990s, the upper level of healthy BMI was revised downward from 27.8 for men and 27.3 for women to 25 for everyone. Overnight, about three million more Canadians were classified as overweight. That shift now looks like a mistake.

We now know that mortality risk throughout much of the overweight range is about the same as in the officially healthy range. The real danger zones for mortality are in the underweight category and the two higher categories of obesity, but most of us don’t live there. Those classes make up just 13 per cent of adult Canadians.

So what’s an ideal body weight or BMI? It doesn’t exist. To say otherwise is to ignore the research on the subject.

Second, the 62 per cent figure doesn’t make allowances for people who choose to carry more pounds simply because they enjoy eating. To an economist, someone is overweight if the marginal cost of the last pound exceeds its marginal benefit. But that’s a subjective evaluation. If someone perceives a high benefit to extra pounds and believes that the extra cost is low, then it’s tough to argue with their decision.

And modern medicine has made it easier to carry around that extra weight. Cholesterol-controlling statins, diabetes and blood-pressure medications and bariatric surgeries have lowered the medical costs of those few extra pounds. The world is full of unintended consequences and this is one of them.

Listening to the anti-obesity advocates, you’d think we were all getting fat on engineered processed snacks, roaming around in food deserts, vainly searching for affordable fruits and vegetables. Research has also rubbished this illusion.

The new villain is big food: companies that manipulate our taste buds, tricking our brains to overeat. But we don’t need corporate deception to overindulge. Just listen to Jonathan Swift in Gulliver’s Travels, written nearly 300 years ago, describing man’s eating habits: “We fed on a thousand things which operated contrary to each other; that we ate when we were not hungry, and drank without the provocation of thirst.”

No one leads us to the trough except ourselves, and no one but ourselves can move us away.

Yet we continually hear that obesity is an unstoppable crisis requiring drastic government action to protect us from ourselves. But such programs are bound to fail. Denmark’s “world famous” fat tax was dumped after one year, when the Danes found the whole mess unworkable. And now they’ve thrown out the tax on soft drinks as well. We should pay attention.

A message to the obesity-industry complex: We can always use more information about the science of obesity, how hormones work and why it’s so hard to shed those extra pounds.

What we don’t need are bloated figures of overweight Canadians and the fallacious policies that are sure to follow. Some of us like the way we are just fine.

Patrick Luciani is co-author of XXL: Obesity and the Limits of Shame, which was shortlisted for the 2011 Donner Prize in Public Policy.